tmetadata.py: skip test_apply_to_path_restricted_access() on Cygwin.

Reported-by: Will Rouesnel <w.rouesnel@gmail.com>
Signed-off-by: Rob Browning <rlb@defaultvalue.org>
metadata.py: ignore posix1e if platform.system() includes CYGWIN.

Reported-by: Will Rouesnel <w.rouesnel@gmail.com>
Signed-off-by: Rob Browning <rlb@defaultvalue.org>